Dehydrating method and apparatus



Dec. 4, 1945.

w. A. PATRICK, JR., HAL 2,390,167

DEHYDRATING METHOD AND APPARATUS Filed May 20, 1943 )ril-443mm: www .izzeafck ,JJ

Zahn Eil/Ader,

Patented Dec. 4,

DEHYDRATING METHOD AND Arrm'rvs Walter A. Patrick, Jr., and John D. Elder, Baltimore, Md.; said Elder assignor to Crown Cork & Seal Company,.lnc., Baltimore, Md., a corporation of New York Application May 20, l1943,-Serial No. 487,780

` 1i Claims. This invention relates to method and `apparatus for the dehydration or concentration of Y' liquid material to a point where the material is still fluid.) Fluidity of the material is required inasmuch as the invention contemplates treatment of the material while in ilow. This requirement is outside of the circumstance that the solid state, as caused by freezing, is in .any event avoided as detrimental to a rapid dehydrating action.

In processes heretofore proposed, the material has been frozen and maintained, so while being sublimed. This procedure is slow and expensive by reason of the low temperature and the high vacuum necessary to be maintained. Whether physical or chemical desiccants are used for the sorption of the evolved vapors the desiccant, in use, undergoes a temperature rise, unless4 controlled, whereby its efficiency is impaired. It is the purpose of the present invention to automatically maintain the material against freezing, for rapid evaporation, and the desiccant against harmful temperature increase, by flowing the material from a zone of forced evaporation through the desiccant in heat exchanging rela' tion therewith.

In some cases, as inthe manufacture of adhesive from blood, it is only necessary to reduce the water content by a relatively small fraction of the original, and in such cases operation under the present invention enables the nal product to be quickly reached. In case a substantially dry product is required, the present invention may be applied as a rapid first stage, and the product, still in liquid state, may be subjected to a second stage. for example utilizing apparatus such as is disclosed in our copending application Serial No. 478,734, led March l0, 1943.

Apparatus in `accordance with the invention is shown by wayv of example in the accompanying drawing, to which reference will now be made.

Reference numeral I designates as a whole an upright container comprising a main portion 2,

former, for example silica gel. A partition I in the conduit 'I has an opening which can be closed by a valve gate I I'. 4

The sump 3 is tapered downwardly to a bottom opening into which is connected a pipe I2 with an interposed valve I3, and connected laterally into the bottom of the sump is a pipe Il which is led through the bottom of vcontainer 9, then zig-zagged through the interior of the container to provide a coil having vertical portions, and then is' extended to terminate in a spray head I5 under the top l of the tank I. A Avalve I6 is interposed in conduit I4 adjacent the sump and beyond the valve a pump I1, of any suitable type, is interposed in the conduit. Fixed to the vertical portions of the coil in container 9 are a multiplicity of heat conducting fins I8 which are in good conductive contact with the conduit, which is itself of good heat conducting capacity, and the spaces between the ki'lns are packed with the desiccant. Between the legs of the coil perforate cylinders I9, for example made of wire mesh, are set'in the container so as to define paths of flow vertically through'the desiccant which is packed about the cylinders. The-pipe Il is led through an opening in the partition III, in which it is sealed, and hasinterposed therein a valve 20 just in advance of a T 2l from which let conduit 26 for the activating fluid leads from the top of the -container 9 and is provided with a valve 21.

A conduit 1' leads from the top of the container I to the top ofa desiccant container 9', the conduit I having therein a partition I0' with an opening controlled by a valve gate II'. A conduit I4 extends from ythe bottom of the sump to and through the container 9', through the partition I0', and to the opposite side of the' T 2| from the conduit I4. Interposed in conduit I4' are the valves I6' and 20' and the pump I1.

Within the container 9'- the conduit I4' isar-` ranged and equipped in the same manner as 9.. The container 9' is connectible with the vacuum source through a pipe 22' and a valve 23'1, and also associated with the container ar the activating air ducts 24' and 26' equipped, respectively, with valves 25' and 21'.

The two desiccant chambers are provided so that one may be used in the dehydrating operation while the desiccant in the other is being regenerated. In the drawing Vit is assumed that chamber i is to be used in the dehydrating process, and this being the case, valves II, I8, 20, and

23 are open, whereas valves I3, 25, and 2B are closed. Valves II', I6', 20', and 23' are closed, and valves 25' and 21' are opened. Consequently, with the suction device in operation, the pressure is lowered throughout the system up to the valve gate II' which isolates the container 9'. It is assumed that hot air is being supplied to thelatter through conduit 2l.

With'the system thus set, and preferably prior to the application of vacuum, the liquid to be dehydrated is introduced in predetermined quantity into the container portion 2 through the top opening 30 upon swinging open the cover 3i.

When the container has been charged the cover is closed and fastened sol as to seal the opening I0. Upon starting pump |1,'the liquid material is withdrawn from the bottom of the sump 3, passed through the coil in chamber 9 and then delivered by the head I5 as a spray on the bodies 6 over which the material ows by gravity substantially in film form so that very large surfaces are provided as an aid to evaporation. The evolved vapors are pulled downwardly through the body of desiccant and are adsorbed thereby. By reason Voi' the evaporationl occurring in the container I the temperature of the material tends to drop, and freezing might eventually occur unless counteracted. 0n the other hand, by reason oi' the condensation of the vapor by the desiccant, the temperature of the desiccant tends to rise. However, the heat oi the desiccant ows into the material in the coil with the result that the temperature of the material is maintained above freezing while the desiccant is maintained at a substantially constant low and efficient operating temperature. The capacity of the desiccant for the purpose of maintaining the material being dehydrated at an above freezing temperature is determined by several factors; for example, whenl silica gel is used, the factors include the area of gel surface exposed to the heat conducting surfaces (i. e., to the coil and the fins I8) thc thickness of the gel layers, and the temperature gradient between the gel and the material being dehydrated. This capacity is so related to the evaporation factors that the material will be maintained at an above freezing temperature and the desiccant will be maintained at an effective operating temperature.

A predetermined quantity of the liquid material having been introduced into the system at the start of the operation, the liquid level in the container I will fall to a certain level in the container when the calculated degree of concentration has been attained as the result of the continued circulation of the -material through the system. In the drawing it is assumed that at this point the liquid will be at the level x in the sump I, the level being observable by means of a -gauge 32 associated with the sump. This level having been reached, valve 2l is closed, the pump is stopped, and valve I 3 is opened so as to drain the dehydrated product from the container. In order to relieve the vacuum condition in the system, valve 21 may, if desired, be opened after valve 23 is closed. The material in pipe Il be.. tween pump I1 and sump 3 will drain back into the latter. When the sump is empty, pump I1 is started and will act to withdraw any further material remaining in pipe Il to the rear ofthe pump and to propel the material in advance of the pump to the head Il so as to clear the pipe I4 throughout.

If the desiccant-dn chamber l is still usable without regeneration, the above-described cycle may be immediately repeated. However, if the desiccant in chamber 9 requires regeneration, the dehydrating operation will be switched to the chamber 9', but before this operation is commenced it will ordinarily be necessary or desirable to flush out the system including the conduit Il. For this purpose, container I is charged with a flushing liquid which is circulated for some time by pump I1. Valve I3 is then opened and conduit y I4 is cleared through the further operation of the pump. When the system has drained, valve I3 is closed, as4 are also valves II.

` I 8. and 2l. Valves 25 and 21 are opened and the troduced into the container I.

activating agent is applied.

The container I having been recharged with material to be dehydrated, valves II', II', 2l', and 23' are opened, and valves 25' and 21' are closed. Upon setting pump I1' in operation. the dehydrating operation proceeds exactly as before except that the desiccant in chamber 9' is now functioning.

Where the material to be' dehydrated has a substantial gaseous content, as in the case of blood, a preliminary degassifying step is desirably used in order to prevent undue foaming during dehydration. Degassication can be very effectively carried out by ilrst freezing the material' and then subjecting it to vacuum. The degassiiled material can then be thawed and in- Or the frozen material can be broken up and introduced into the container in this form. In the latter case, in order to accelerate thawing, heat can be supplied by causing a ilow of hot air through the top of container I, for example by opening valves 25 and 21 while valve 21 remains closed. While we emphasize the carrying out of the dehydrating operation with the material in liquid form, thisI of course, does not preclude the described preliminary freezing for the purpose oi' facilitating a degassifying operation.

It will be understood that the disclosed apparatus is merely representative and that variations therein and in procedural matters are possible under the invention and contemplated in the claims which follow.

We claim: l

l. In the dehydration of a liquid material by the subjection of the same to forced evaporation and by the sorption of the evolved vapors in a desiccant, the method of heating the material and cooling the desiccant which comprises flowing a stream of the material being dehydrated in heat exchanging relation with the desiccant.

2. In the dehydration of a liquid material by the subjection of the same to forced evaporation and by the sorption of the evolved vapors in a desiccant, the method of heating the material and cooling the desiccant which comprises cir- `,culating the material through a zone wherein it material in heat exchanging relation with the latter,

4. Apparatus for dehydrating a liquid material comprising a. container for the material, a body of desiccant, a vapor suction line in connection with said container and in communication with said body of desiccant, and a circulatory system for the material including said container and including a portion passing through said body of desiccant whereby to provide for heat exchange between the latter and th'e material in said portion. 1

5. Apparatus for dehydrating a liquid material, comprising a container for the material, a conduit arranged to withdraw material from the container and to return the material thereto, a pump for moving the material through said conduit, a body of desiccant through which the conduit passes so that material in the conduit is brought into heat exchanging relation with said body, and a vapor suction line in connection with said chamber and in communication with said body.

6. Apparatus according to claim 5 wherein means is provided for delivering the material from the conduit to the container as a spray.

7. Apparatus according to claim 5 wherein the container contains a multiplicity of bodies onto which the material is delivered by said conduit for flow thereover substantially in iilm form.

8. Apparatus according to claim 5 wherein means is provided for delivering the material terial in the conduit is brought into heat exchanging relation with said body, and a vapor suction line in connection with said container and including said body,

l0. Dehydrating apparatus for liquid material comprising a container for the material, a pair of desiccant containers, valved vapor conduits connecting the material container with the desiccant chambers respectively, valved suction conduits in connection with the desiccant containers respectively, valved inlet and outlet conduits for an activating iiuid in connection with each desiccant chamber, whereby suction may be applied to the material container through either desiccant chamber while the desiccant in the other is being activated, and means for eiecting heat exchange between the material and the desiccant in the from the conduit to the container as a spray, and a wherein the container contains a multiplicity of bodies which receive the material for flow thereover substantially in film form.

9. Apparatus for dehydrating a liquid material. comprising a, container for the material, a conduit extending from the bottom of said container to a delivery point above the container, a pump interposed in said conduit operative to move the material through the circuit constituted by said container and conduit, a body ,of desiccant through which the conduit passes so that machamber through which' suction is being applied.

1l. Dehydrating apparatus for liquid material comprising a container for the material, a' pair of desiccant containers, valved vapor conduits connecting the material container with the desiccant chambers respectively, valved suction conduits in connection with the desiccant containers respectively, valved inlet and outlet conduits for an activating iiuid in connection with each' desiccant chamber, whereby suction may be applied to the material container through either desiccant chamber while the desiccant in the other is being activated, a circulatory system including the material container and one of the desiccant containers, a circulatory system including the material container and the other of the desiccant containers, and means for rendering said systems selectively operative so that only thev system including the desiccant chamber through which suction is operative whereby heat exchange will be eil'ected between the material and the desiccant in the last mentioned container.

WALTER A. PATRICK, Jn. Joan D. ELDER.

being applied will be 

